Serious about seed potatoes

CEO of Agrivan Farming in North West, Werner du Plessis, spoke to Gerhard Uys about farming seed potatoes and how his business has remained at the top of its game for over 25 years.

Serious about seed potatoes
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Farming potatoes is in itself a specialised field, while growing seed potatoes is an even more specialised field within it.
Agrivan Farming, situated near Christiana in North West, has 28 years’ experience in seed potato farming and has ensured the quality of its product by taking full control of the value chain.

In partnership with WesGrow Potatoes, Agrivan manages every step – from propagation material to supplying clients with certified commercial seed – and this has set it apart from producers outsourcing certain legs of the process. Considering that it takes four to five years for a mini-tuber to reach the stage where it can be sold to a potato grower, controlling the value chain in this way is a long-term commitment.

Cultivar varieties

“In terms of genetic progress, we have to think four to five years ahead,” says Werner du Plessis, Agrivan CEO. “The process starts with cultivar owners in Holland and Ireland supplying propagation material to Rascal Research Laboratories in South Africa.”

Agrivan cultivars are comprised of 50% Mondial, 37% Sifra and 4% Innovator, while the other 9% to 10% is used for the development of new cultivars.Panamera, Electra and Savannah are promising future prospects. “The current market share held by WesGrow and the constant change in market demands [are the key factors] in choosing the varieties that we grow,” Werner explains.

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When developing a new cultivar, it is important to understand the market and its needs, he stresses. In addition, adaptability in terms of climatic and other growing conditions in different regions is a major factor. Exporting to countries in the Southern African Development Community means understanding a foreign market.

“If our choice of cultivars was based only on profit, new cultivars would probably not be more than 2% to 3% of our annual planting. Fortunately, we share WesGrow’s vision of staying ahead of our competitors. Constantly developing new cultivars for South Africa and its various climatic zones is a vital part of being sustainable. Our region can handle a rather wide range of cultivars, [and is] thus very suitable for the purpose.”


According to Werner, Agrivan Farming and WesGrow have a close working relationship. “This ensures that we follow the golden rules of seed growing and are able to supply a top-quality product – and that distinguishes us from our competitors. Following and constantly developing our ‘game plan’ in partnership with WesGrow ensures our sustainability.”

WesGrow and their shareholders and growers all follow one common strategy regarding the production of seed potatoes and voluntarily subscribe to certain values that take the business forward.For example, Agrivan has an eight-year crop rotation system and only plants eragrostis and oats in this system.

“We have to reinvest in soil as a key resource and re-establish the veld and nutrients taken from the ground as soon as possible. We plant eragrostis and give the veld enough time to recover. Natural growth cycles of various grasses restore soil structure and organic matter.”

Werner explains that WesGrow did not enforce the system, but he and his team regard it as a sustainable practice.
“It’s less profitable in the short term, but ensures profitability in the long term. We have to think of the next generation’s success.”

Werner du Plessis

Seed and tubers

The total annual Agrivan potato planting is registered under the national certification scheme and only certified seed is planted. About 25% of the total harvest is marketed and used as certified seed, with 75% marketed as table potatoes.

“The whole harvest is suitable for seed, and size is the only determinant between seed and table potatoes,” Werner explains.

Potatoes of 100g and smaller are marketed as seed, while anything above is for the table market. The seed market is supplied with 25kg pockets. The number of tubers per pocket ranges from 250 to 600, and clients normally get what they prefer. Table potatoes are sold to various markets in 7kg and 10kg pockets.

Depending on climate region and grower type, plant densities vary from 25 000 tubers/ha to 70 000 tubers/ha, with a national average of around 160 bags of seed per hectare.

“Our growth period for seed potatoes is 90 days to 110 days, which is shorter than the normal growth period,” says Werner. “The art is getting a high enough yield in a limited time. High yield in itself is not that difficult, but we need good volume by balancing the number of units and the size thereof. Producing enough units of the right size is our main objective, but there’s a fine line to achieving that.”

He explains that growing seed potatoes is a perfect triangular relationship between good yield, enough tuber units per plant and minimal virus infection.

Disease control
According to Werner, a seed grower’s biggest risk is a lack of control of volunteer plants on the previous year’s post-harvest plantings. These plants increase the risk of virus infection on the current planting. This risk is eliminated by good post-harvest control methods – both chemical and mechanical – and active, sustainable management thereof. Potato Leaf Roll Virus (PLRV) and Potato Virus Y are the most common and influential viruses threatening seed growers in SA.

They are carried by aphids and the longer the growth period, the larger the risk of infection. The physiological status of the potato plant determines the risk of infection, with the latter part of the growth period being the most risky. Good chemical control throughout the season, a well-trained and committed volunteer plant team, as well as a shortened growth period, lowers this risk.

“WesGrow differentiates from competitors’ due to the fact that we maintain lower tolerance levels than the national standard: PLRV at only 2,5% instead of 5%, as the national certification scheme indicates. “The core principle of growing potato seed is planting top-quality seed, that’s why we remain in control of the whole multiplication process.

“[The second principle] is a good crop rotation system and a suitable crop in that rotation system. You also need a ‘potato-free’ time where you are assured that transmission of disease is curbed. This is done by making sure all volunteer plants are controlled well.”

Werner says that neighbouring seed growers have a direct influence on each other: “We’re not just managing a farm, we’re managing a region.”

“We aim to use only the best products and methods, ensuring that our yield and quality remain at the highest level.  However, there’s a balance between benchmarking input cost and diminishing returns, and we constantly strive to stay on the line,” says Werner, explaining that he and his team are output- rather than input-driven.

Plants are killed when still in the growing phase using chlorine-free fertiliser. “We also have a blue-chip pesticide programme and do not multiply one source’s seed more than twice.”

Soil preparation starts nine to 12 months before planting and lands are kept clean throughout the season. “We rip soil four times throughout this process and belt-feed 60% of our fertiliser to make sure we hit the target.”

Challenges ensure that Agrivan remains innovative, with sustainability regarding natural and human resources being the most significant. Repetition is also a challenge. “We do the same thing every year, and every year we have to be better. It’s a challenge once you reach ‘acceptable’ levels of production and have to keep on raising the bar. With potatoes, one can let that culture thrive. There’s always a better plan to make.”

Despite the sometimes frightening realities facing the country’s farmers, Agrivan remains positive and reinvests a substantial part of its profits back into the business. According to Werner, farmer numbers are decreasing and farming units are becoming bigger, and thus the need for competent management is increasing.

“Various career types exist within agriculture and the opportunities are there, but the old mental block of needing land is still there. We need top young people to join our industry and build careers within it. Owning land didn’t influence my career choice.”

Labour relations
Agrivan employs about 250 permanent workers and seasonally hires an additional 500 workers. “We are used to having labour in our industry,” says Werner. “We positioned ourselves to train labourers, pay them more and build our business together. We don’t try to run away from it, we build relationships that’ll last in the long term.”

He explains that although Agrivan has mechanised to an extent, he deliberately did not try to save more than 20% labour. “We have an ethical obligation to create employment.”

Permanent staff receive bonuses based on production figures and profit. Sharing prosperity with the workforce results in earning workers’ trust and inspiring them to take ownership of their work, Werner explains.

Phone Werner du Plessis on 082 456 5744 or email him at [email protected].

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Gerhard Uys grew up as a real city lad, but spends his free time hiking and visiting family farms. He learnt the journalism trade as a freelance writer and photographer in the lifestyle industry, but having decided that he will be a cattle farmer by the age of 45 he now indulges his passion for farming by writing about agriculture. He feels Farmer’s Weekly is a platform for both developed and emerging farmers to learn additional farming skills and therefore takes the job of relaying practical information seriously.